grammar - Subject in English

I'm Japanese and I am studying English, in particular, reading English books. I have some questions about the subject.

We also use pronouns in Japanese. Then, a subject usually does not change from line to line. For example, if we say the following sentence in Japanese,
"Lon wrote a letter. He sent it to Jacob. He was excited."
then the last "he" means Lon; whereas, if we say the above in English, the last "he" can mean both "Lon" and "Tom", as I studied.

In English, isn't it hesitated to change a pronoun from line to line?

Best